In sectional doors torsion springs serve for compensating for the different effective weight forces of the sectional doors. To this end, the torsion springs torsion-elastically support shafts of rope drums, on which holding ropes for the sectional doors are wound.
To achieve a torsion-elastic support by means of a spiral torsion spring, the ends of the torsion spring are to be fastened on the one side to a fixed part of the door construction, for example, and on the other side to the shaft to be supported, each time in a manner which is resistant to torsion loads. A so-called fixed cone is used on the one side, and a so-called clamping cone is used on the other side. The generic term used here for both of these two cones is spring holding cone. The name “cone” is attributable to the fact that the outside surface which supports the torsion spring at its internal diameter conically increases in diameter in the axial direction away from the torsion spring in most of these devices. The conical shape of the outside surface is to be adapted to the inside diameter of the spiral torsion spring that contracts under torsion load. Instead of a conical outside surface steadily increasing in size, an outside surface which increases in size step by step can be provided.
A known spring holding cone has two securing elements, which are two clamps to be fastened to a main body by means of screws for holding the first spring turn of the torsion spring at the spring end. The two clamps have to be adapted to the relevant spring wire thickness and the relevant spring diameter, and they are arranged opposite to each another at an offset of 180° of the circumference of the outside surface. Further, the known spring holding cone has coaxial fastening holes, in order to use it on one hand as fixed cone and on the other hand in connection with a clamping part as a clamping cone. A disadvantage of this known spring holding cone is that it does not hold the spring end positively but only non-positively, i.e. by means of friction between the cone and the spring wire, and that the expenditures for installing the spring end on the spring holding cone are quite high. The same clamping part may, however, be used with spring holding cones of different sizes for different inside diameters of the torsion spring because of the same spacing of the fastening holes in these cones.
A further known spring holding cone has a projecting from its outside surface and forming an external thread on the outside surface which is to be screwed-in between the spring turns of the torsion spring. Afterwards, the spring end is to be heated up and then the end of the spring wire is to be bent over into a recess within the outside surface for fixing the spring end to the spring holding cone in a positive and torque resistant way. As a result, the expenses for attaching the spring holding cone to a torsion spring are very high. Moreover, this known spring holding cone is provided in two different embodiments as a clamping cone with integrated clamping part, on the one hand, and as a fixed cone, on the other hand. In smaller production series this reduces the utilization of tools for forming the spring holding cones. It must also be considered that due to the,external thread formed by the flank on the outside surface of the known spring holding cone the spring holding cone is suitable only for torsion springs in a certain direction of thread, and additional embodiments of the spring holding cones are required for the opposite direction of thread.
It is an object of the invention to provide a spring holding cone which can be both manufactured and assembled economically.
It is a further object of the invention to provide a spring holding enabling an easy positive fixation of the spring end to the spring holding cone.